It is sometimes desirous to color bottles or to make them translucent or opaque in order to improve their appearances. Conventionally known methods of making such translucent or opaque bottles, i.e. frosted bottles, of synthetic resins are to use a mould having a roughened inner surface provided with numerous minute scars or scratches, or to corrode the surface of a transparent bottle. However, the bottles made by any of the conventional methods described above have disadvantages in that minute projections and recesses are formed on the surfaces thereof, similar to ground glass, to become unpleasant to the touch, and that they may be easily soiled due to adhesion of dusts and oily material transferred from the hands into the recesses or on the projections, and that the appearances thereof are spoiled since luster of the surfaces has been lost. Moreover, said roughened mould is expensive since complicated operations are required to manufacture the same, which results in increase in production cost of the moulded bottle.